Temperature-dependent Kelvin probe measurements of band bending in p-type GaN

Abstract

The band bending in a Mg-doped, p-type GaN film grown by hydride vapor phase epitaxy was studied at various temperatures. At 295 K, the band bending in dark was calculated to be approximately À1.5 eV. However, when the sample was heated to 600 K for 1 h in dark before performing a measurement at 295 K, the calculated value of band bending in dark became about À2.0 eV. These results are explained by the fact that increasing the sample temperature exponentially increases the rate at which the band bending restores and allows for a more accurate value of band bending to be measured. V

p-Type dopant incorporation and surface charge properties of catalyst-free GaN nanowires revealed by micro-Raman scattering and X-ray photoelectron spectroscopy

“…It results in a weakly n-type surface of nanowires, which is well correlated with the commonly measured downward surface band bending for p-type GaN. [50][51][52][53] This unique phenomenon also leads to the coupling between the LO phonon and the surface electron plasmon presented in the Raman spectra. Such accumulated surface electrons are gradually compensated by enhanced Mg incorporation with higher T Mg .…”

Localized Charge Transfer Process and Surface Band Bending in Methane Sensing by GaN Nanowires

“…where  is the static dielectric constant of GaN (9.8), 39  0 is the permittivity of free space, N D is dopant concentration, and n s is surface charge density.…”

Temperature‐dependent Kelvin probe studies on GaN from 80 to 600 K

“…In particular, this method is useful for investigating the nearsurface band bending and the effects of light, ambient, and temperature on the electrical and optical properties of the near-surface region. The reported values of band bending for GaN are about 1 eV upwards for n-type [1,2], and 2 to 3 eV downwards for p-type [3][4][5], and it is attributed to the accumulation of negative or positive charge at the surface, respectively. The band bending can be reduced by illuminating with ultraviolet (UV) light, and the reduction can be detected by the Kelvin probe as a surface photovoltage (SPV) signal.…”

“…Typically, Kelvin probe measurements are performed at room temperature, and very few works can be found where the band bending or SPV are studied at any other temperature [3,4]. Previously, we reported on SPV measurements of n-and p-type GaN with a Kelvin probe for the temperature range of 300-600 K [5,10]. In these studies, we have established that the band bending in dark is nearly independent of temperature and equal to 1 eV and -2 eV for n-type and p-type GaN, respectively [5,10].…”

“…Previously, we reported on SPV measurements of n-and p-type GaN with a Kelvin probe for the temperature range of 300-600 K [5,10]. In these studies, we have established that the band bending in dark is nearly independent of temperature and equal to 1 eV and -2 eV for n-type and p-type GaN, respectively [5,10]. For both types of materials, and especially for p-type, "pre-heating" the samples in dark at temperatures higher than 500 K for several hours is necessary to fully restore the band bending after illumination.…”